The present application finds particular application in controlling compressors for commercial hybrid vehicles. However, it will be appreciated that the described technique may also find application in other compressor systems, other vehicular systems, or other control systems.
In conventional screw-type compressors, an example of an electrically controlled compressor, a pair of helical screws or rotors is employed to compress a gas, such as air. Oil-filled screw compressors employ a lubricant that fills the space between the rotors. The lubricant provides a hydraulic seal and transfers mechanical energy between the screws. Air enters at a suction side and moves through the threads as the screws rotate. In this manner, the rotors force the air through the compressor until it exits at the end of the screws.
Currently in heavy duty hybrid vehicle design, there is an effort to electrify vehicle subsystems to move them off the engine. As these subsystems are electrified, there is a need to intelligently control and optimize their power usage to be in concert with the entire vehicle electrical system. For example, there is a problem with existing electric air compressor subsystems within heavy duty hybrid vehicles. Presently, electric air compressor systems are not designed to manage and modify their operation to control and optimize the energy used to charge the air tanks for air brake and other pneumatic systems. That is, conventional electric compressor systems on heavy duty hybrid vehicles do not include an intelligent control of the energy required to maintain the air pressure. These systems do not monitor and utilize existing vehicle information to modify their operation to optimize energy conservation.
Existing compressor systems normally turn the compressor On or Off at fixed speeds and pressures. For instance, the compressor is On at full speed at the lower pressure (CUT IN) and Off at the higher pressure (CUT OUT). Existing electric compressor systems cannot dynamically alter their operation to help conserve and store energy. These electric compressor systems have no means to optimize the energy usage required to maintain the vehicle air pressure or modify the compressor operation based upon vehicle status or energy demands.
Presently, compressor control systems do not have the capability to dynamically vary the motor speed (RPM) or change the CUT IN and CUT OUT pressure thresholds as vehicle operational status and power requirements change. Vehicle operational status information is available on the vehicle communication bus (J1939 CAN or equivalent). There is a problem with existing systems in that these systems do not communicate over the bus or use available information to modify the electric compressor operation to be in harmony with the vehicle system to conserve energy. Moreover, existing air compressor control systems cannot modify their operation based on the high voltage battery state of charge (SOC). Existing systems do not access or use information regarding the SOC or the status of brake energy available for regenerative braking (regen) so as to optimize energy usage.
The present innovation relates to systems and methods that overcome the above-referenced problems and others.